Fnord wrote:
Simple. You tell them.
Think of being offered the most disgusting food you can imagine (sushi, liver, balut, et cetera), then politely and firmly say the first thought that comes to mind.
Please don't do this. There's no reason to use a sledgehammer when a simple firm application will do just as well. Don't destroy the person or lose a future ally.
Just don't be overly polite, and don't lead them on. Don't let her make a date with you, don't agree to spend time together, she'll get the hint.